Fireproofing textile material



I Patented 1936 UNITED STATES mnnrnoorme TEXTILE MATERIAL WilliamAlexander Dickie and Frank Brentnall Hill, Spondon, near Derby, England,assignors to Celanese Corporation oi America,'a corporation of DelawareNo Drawing. Application October 16, 1931, Serial 5Glaims.

This invention relates to a treatment of textile materials in order toimprove their resistance to fire.

One of the most important points to be considered in dealing with atextile material .is to remove or lessen the danger of fire either fromthe infiammability of the material itself or from hot or burning piecesof the material igniting other objects. A number of substances have beenused in order to render textile materials fireproof", and a considerabledegree of. success has been obtained. The difficulty of obtainingefiicient fireproofing is however increased in dealing with fabrics madeof or containing organic derivatives of cellulose. These derivatives ofcellulose are not usually considered highly inflammable, but at the sametime there is added a danger that drops of the molten burning materialmay ignite other inflammable materials.

It has now been found that efflcient fireproofing can be obtained fortextile materials in general, and especially for cellulose derivativematerials, by applying to the materials a substance or compositionwhich, under the action of heat, will yield products which willextinguish a flame, and will also yield products which will hold the hotor charred material together.

Suitable compounds or compositions for earlying this invention intoeffect are the borates of volatile bases or mixtures of boric acid withsalts having a volatile base, or of borates or phosphates with saltshaving a volatile base. .The salts of ammonia and especially theammonium halides, such for example as ammonium bromide, are excellentexamples of salts having a volatile base which may be employed in thesemixtures.

As examples of compounds or compositions which may be used forfireproofing textile materials mixtures of ammonium phosphate and boricacid, or of ammonium phosphate and ammonium borate and ammonium boratealone may be mentioned. The best composition for use in fireproofing acellulose derivative material has however been found to be a mixture ofammonium borate or phosphate with an ammonium halide such as ammoniumbromide, the added ammonium halide appearing greatly to increase theflame extinguishing properties of the ammonium borate or phosphate. Inany of the above compounds or mixtures the ammonium base may be replacedby another volatile base, for example an organic base.

This invention may be applied to the fireproofing of textile materialsof all kinds. Thus for example cotton, jute, regenerated cellulose or InGreat Britain December 20,

other cellulosic materials, wool or silk materials may be treated butthe process is of greatest value for fireproofing materials made whollyor in part of cellulose derivatives, for example cellulose acetate,cellulose formate, cellulose propionate, cellulose butyrate, or othercellulose ester, or ethyl cellulose, methyl cellulose, benzyl Icellulose or other cellulose ether.

In the caseof treating materials made of or containing organicderivatives of cellulose, such as those mentionedabove, improved resultsmay be obtained by combining the fireproofing treatment of the presentinvention with a treatment designed to. weight the material with asuitable insoluble metallic compound, as for example a phosphate,silicate or other compound of tin. Such weighting treatments are ingeneral carried out by introducing the metallic radicle necessary forthe formation of the weighting compound under such conditions thatswelling of the cellulose derivative occurs. Such swelling may takeplace in the weighting metal bath itself or in a pretreatment appliedfor the specific purpose. Thus suitable swelling agents may be appliedto the materials before or together with the weighting metal solution,as for example stannic chloride. Thiocyanates are very suitable for thispurpose. An alternative method consists in employing the weighting metalcompound, as for example stannic chloride, in a sufllcient concentrationor at a sufllciently high temperature to swell the cellulose derivativeor in employing a compound of the weighting metal which is itself aswelling agent, as for example stannic thiocyanate or stannicchlorothiocyanate. The weighting treatment raises the ironing point ofthe material, and in conjunction with the fireprooflng treatmentcharacteristic of the invention produces a greatly improved product.Such weighting treatments may b e applied at any suitable time inrelation to the application of the fireproofing treatment. Preferably,however, the weighting treatment is applied before the flreproofingtreatment.

Again in the flreprooflng of materials made of or containing a celluloseester additional safeguards may also be applied, for example bysubjecting the cellulose ester material to a partial or superficialsaponification, e g. to an extent corresponding to a loss of 3% of theweight of the fibre.

The treatments may be applied to the materials at any stage oi theirproduction or treatment and may be applied together with othertreatments.

to its being made up into fabric, it may be applied to the fabric, or toan article made from the fabric.

According to one mode of carrying the invention into efiect the materialto be treated is impregnated by immersion in a solution of the compoundor composition to be applied, and is then wrung out and dried. Drying ofthe fabrics may take place for example on a stenter. Other methods ofimpregnation, such for example as padding, printing or spraying may beemployed.

The following examples illustrate the invention but are not to beconsidered as limiting it in any way. In particular considerablevariations may be made in the proportions of fireproofing substancesapplied and in the concentrations in which they are applied.

Example 1 A cellulose acetate fabric is immersed for a short time in anaqueous solution containing 20% of ammonium bromide and 5% of ammoniumborate. The fabric is wrung out and dried on a stenter. Instead ofapplying the fireproofing agents by a bath treatment they mayconveniently be applied by a padding treatment.

Example 2 Previously scoured cellulose acetate fabric is entered andsteeped for 1 hour with occasional turning in a bath maintained at about20 C. containing 280 grams per litre of stannic chloride (SnCl4.5I-I2O)and 243 grams per litre of ammonium thiocyanate. It is then lifted,drained well and washed, first in two baths of cold water and then intwo baths of water at 45 C. until free from soluble salts. The goods arethen entered into a bath at C. containing 12% of sodium dihydrogenphosphate, worked for hour, lift- Example 3 Previously scoured celluloseacetate fabric is entered into a bath at 20 0. containing 280 grams ofstannic chloride and 182 grams of ammonium thiocyanate per litre. Aftersteeping for 1 hour with occasional turning the goods are lifted,drained, washed and further treated as described in Example 2 for thefixation of the tin compound. After rinsing the goods are padded with anaqueous liquor containing 15% of ammonium bromide and 10% of ammoniumphosphate. They are then dried as described in Example 1.

What we claim and desire to secure by Letters Patent is:--

1. Process for the treatment of materials comprising organic derivativesof cellulose which comprises applying a weighting treatment to the saidmaterials and then applying to the said materials a halide of a volatilebase and a substance selected from the group consisting of a phosphateof a volatile base and a borate of a volatile base.

2. Process for the treatment of materials comprising cellulose acetatewhich comprises applying a weighting treatment to the said materials andthen applying to the said materials a halide of a volatile base and asubstance selected from the group consisting of a phosphate of avolatile base and a borate of a volatile base.

3. Process for the treatment of materials comprising cellulose esterswhich comprlses applying a weighting treatment to the said materials andthen applying to the said materials a halide of a volatile base and asubstance selected from the group consisting of a phosphate of avolatile base and a borate of a volatile base, and which also comprisesthe step of saponifying the materials.

4. Process for the treatment of materials comprising cellulose acetatewhich comprises applying a weighting treatment to the said materials andthen applying to the said materials a halide of a volatile base and asubstance selected, from the group consisting of a phosphate of avolatile base and a borate of a volatile base, and which also comprisesthe step of saponifying the materials.

5. In a process for the manufacture of mate rials comprising organicderivatives of cellulose,

which the materials are weighted with an i 'soluble metal compound, thestep which consists in applying to said materials a halide of a volatilebase and a substance selected from the group consisting of a phosphateof a volatile base and a borate of a volatile base.

WILLIAM ALEXANDER DICKIE. FRANK BRENTNALL HILL.

